VulnerabilityPublished 1 May 2026Updated 19 Oct 2026

CVE-2026-31708: Linux kernel · Out-of-bounds Read

Affects Linux kernelSource CVE Database V5

Not known to be exploited · CVSS 8.1 High · fixed in e66bdc0704977ecee667a81d38255b579c2353d0 : patch Linux kernel soon.

Data as of 26 Oct 2026, 17:30 UTC

CVSS 3.1 base score

8.1High

How severe the flaw is on the 0–10 CVSS scale.

EPSS

0.3% chance of exploitation in 30 days – higher than 28% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

Exploitation: No evidence of active exploitation and no public proof of concept
Automatable: Attackers cannot reliably automate steps 1–4 of the kill chain
Technical impact: Limited control over the software or limited information exposure

CISA SSVC assessment, 2026-10-16.

Patch

Available – fixed in e66bdc0704977ecee667a81d38255b579c2353d0, ac2f14e4705d020f04e806efa0d49ab8dc2b145f, a58c5af19ff0d6f44f6e9fe31e33a2c92223f77e +5

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:H

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: Required
Scope: Unchanged
Confidentiality: High
Integrity: None
Availability: High

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: Required: Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 1 May 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ f5778c398713692a16150ae96e5c8270bab8399f, < e66bdc0704977ecee667a81d38255b579c2353d0	Fixed in e66bdc0704977ecee667a81d38255b579c2353d0
LinuxLinux	Affected ≥ f5778c398713692a16150ae96e5c8270bab8399f, < ac2f14e4705d020f04e806efa0d49ab8dc2b145f	Fixed in ac2f14e4705d020f04e806efa0d49ab8dc2b145f
LinuxLinux	Affected ≥ f5778c398713692a16150ae96e5c8270bab8399f, < a58c5af19ff0d6f44f6e9fe31e33a2c92223f77e	Fixed in a58c5af19ff0d6f44f6e9fe31e33a2c92223f77e
LinuxLinux	Affected ≥ f5778c398713692a16150ae96e5c8270bab8399f, < a34d456934fe42e4da5d2cc07787bf418bee99c6	Fixed in a34d456934fe42e4da5d2cc07787bf418bee99c6
LinuxLinux	Affected ≥ f5778c398713692a16150ae96e5c8270bab8399f, < 85fd46ee26a11841c670449508025965f61ce131	Fixed in 85fd46ee26a11841c670449508025965f61ce131
LinuxLinux	Affected ≥ f5778c398713692a16150ae96e5c8270bab8399f, < 078fae8f50adebb903ccf2252b44391324571e78	Fixed in 078fae8f50adebb903ccf2252b44391324571e78

AI-suggested

This vulnerability has been fixed in the Linux kernel. Users and administrators should apply the official kernel updates that include the fix identified by the listed commit hashes. Since this is a kernel vulnerability, patching the kernel to a fixed version is the recommended and effective mitigation. No additional workarounds or mitigations are indicated.

Description

CVE-2026-31708 is a high-severity vulnerability in the Linux kernel's SMB client implementation. It involves an out-of-bounds (OOB) read in the smb2_ioctl_query_info QUERY_INFO path. A malicious SMB server can exploit this flaw by returning a larger OutputBufferLength than the actual response, causing the kernel to copy more data than intended and potentially exposing adjacent kernel heap memory to userspace. The issue is fixed by adding proper bounds checking on the copied buffer to prevent overflow.

Impact

An attacker controlling an SMB server can exploit this vulnerability to cause an out-of-bounds read in the kernel, potentially leaking sensitive kernel heap memory to userspace. This can lead to information disclosure, which may aid further attacks. The CVSS score of 8.1 reflects high severity with network attack vector, low attack complexity, no privileges required, user interaction required, and high confidentiality impact. There is no indication of known exploits in the wild.

CWE-125Out-of-bounds Read (opens in a new tab)
Base weaknessCWE Top 25 (2025): #8
The product reads data past the end, or before the beginning, of the intended buffer.
Implementation · Input Validation
Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
Architecture and Design · Language Selection
Use a language that provides appropriate memory abstractions.
OWASP Cheat Sheets
XML Security (opens in a new tab)
Mass Assignment (opens in a new tab)
OWASP ASVS 4.0.3
V13.3.1 (opens in a new tab)
V5.1.4 (opens in a new tab)
V5.1.3 (opens in a new tab)
Attack patterns
Overread Buffers (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 26 Oct 2026, 15:54 UTC

WeaknessesCWE-125

Technical details

References

Community reviews

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